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‘Insufficient and unconvincing’ scientific evidence to promote acai, says review

By Nathan Gray , 16-Mar-2011
Last updated on 22-Mar-2011 at 15:23 GMT

One of the most highly praised nutraceuticals of the decade – açai – has “insufficient and unconvincing scientific evidence” to promote it as an exceptional health supplement, according to a new review.

The new review, published in Phytochemistry Letters argues that strategies need to be developed in order to prioritize lesser studied ‘novel’ herbal medicines and nutraceuticals that are widely distributed or popularized via the internet, in order to critically assess the benefits and risks of such products and evaluate the claims made.

“Açai is one of the first examples of the marketing power of the internet and the spread of local products to a global market using the World Wide Web,” said the authors, led by Michael Heinrich, from the Center for Pharmacognosy and Phytotherapy, at The School of Pharmacy (University of London), UK.

They explained that although the evidence to support the claims for açai remains unconvincing, Google searches for açai steadily increased between 2004 and 2008, before “a dramatic increase of interest in açai” in 2008 and 2009.

Heinrich said that popularity of açai “is a poster child of the power of the internet to promote products for which only limited phytochemical and pharmacological information is available.”

Premature

Commenting on the review, Dr Alex Schauss, CEO and senior director of natural and medicinal products research at AIBMR Life Sciences and a well established açai researcher, said the new review was “interesting but premature given the wealth of papers on açai to be reported that are in press and recently submitted by various research groups.”

Despite an “incomplete” overview of açai botany, constituent and bioactivities of açai, Dr Schauss said that the authors “do provide a fascinating analysis of the influence of Opray Winfrey and Dr. Oz that arose during a discussion of açai on the Oprah Show some years ago that spark considerable interest by the public to learn more this fruit”.

“Unfortunately, the interest generated led to unsubstantiated claims on the Internet broadcast to millions that açai and resveratrol caused weight loss, primarily designed to obtain credit card information from an unsuspecting public by unscrupulous entities that have become the subject of FDA and FTC investigations,” he added.

Argument for açai

The palm Euterpe oleracea Martius (açai) has been claimed to have a wide range of health-promoting and therapeutic benefits, due to its reportedly high levels of antioxidants.

The authors noted that açai has a history of use as a medicinal plant, and is a staple food in many parts of Brazil, where traditionally it has been also used to treat fevers, skin complications, digestive disorders and parasitic infections.

In recent years açai has been marketed as a dietary food supplement; claiming to have superior health benefits including rapid weight loss, improving digestion, fighting cardiovascular disease and preventing the process of aging.

Heinrich and his colleagues said that in recent years several manufacturing companies have “aggressively marketed açai berry products” such as tablets, juices, energy drinks, powders and smoothies – mostly in North America (mainly the United States), Europe and Japan.

The major claims on these adverts include rapid weight loss, improving sexual (dys-)function, to be the secret to longevity and to have anti-aging properties, which gave rise to major concerns by the FDA - a point also noted by Dr Schauss.

Review details

The reviewers explained that the predominant chemical constituents in açai are polyphenols – most notably anthocyanins and flavonoids.

They said evidence for the overall pharmacological effects relating to antiproliferative, anti-inflammatory, antioxidant, and cardioprotection activities of açai are “lacking in clear and conclusive data.”

“Leaving aside the question whether in vivo effects can be extrapolated from in vitro anti-oxidant data (which is highly controversial) … evaluating açai data on a comparative basis with other ‘anti-oxidants’ proved to be a challenge,” added Heinrich and his colleagues.

They explained that overall, based on the current literature, açai “does not seem to have superior antioxidants levels,” with evidence pointing towards variable antioxidant capacities.

They added that although in vitro and in vivo studies have been assessed, in order to determine the therapeutic potential of açai; the results of such studies have been “mostly inconclusive.

The reviewers did however conclude that açai demonstrates “promising potential” with regard to its anti-proliferative activity and cardio-protection, but said that further studies are needed in order to confirm such benefits.

They added that such future research should focus on more rigorous intervention studies or clinical trials carried out over an extended periods of time and with large sample populations.

Watch this space

In an email to NutraIngredients-USA, Dr Schauss noted that a number of papers are expected to appear in 2011 in the scientific literature, including an upcoming paper in Atherosclerosis that provides açai’s mechanism of actions based on two in vivo studies, while another paper in press to appear in the Journal of Medicinal Foods will further support reports of the benefits based on a human clinical trial of older adults, he said.

“The time for a review, given the evolving science studying açai at numerous academic and government institutions, may have best been served if the authors had waited until 2012, when many of the publications in submission, submitted, in press, and recently published, would all have been in the public domain to appreciate the totality of evidence in support of the health benefits of açai,” added Dr Schauss.

Source: Phytochemistry Letters
Volume 4, Issue 1, Pages 10-21, doi: 10.1016/j.phytol.2010.11.005
“Açai (Euterpe oleracea Mart.)—A phytochemical and pharmacological assessment of the species’ health claims”
Authors: M. Heinrich, T. Dhanji, I. Casselman

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